You mean the meals in the book? You can have those at any time - the book has recommendations for portion sizes to start with. Try to think of it as “as many portions as you NEED” rather than want, don’t stuff yourself just because you think you can. I wouldn’t do dessert with every meal, but if you’re following the meal & snack guidelines, you probably won’t want to, either.
And don’t feel like you have to eat only the meals in the book - those are just meant to be suggestions and recipes, not the only meals you can eat. Make meals out of whatever is on the food list, as long as you’re following the other guidelines.
As for phase 3, you have to figure it out for yourself. It’s the maintenance phase, so you’re allowed to snack, you just need to see what works for you when you get there.